1. Field of the Invention
The present invention relates to a process for producing a fertilizer from free bark, and particularly to a process which is an improvement on that disclosed in Finnish Patent No. 44,124.
2. Description of the Prior Art
Bark has been used for fuel and land improvement. In the latter purpose bark has, for example, been composted using bacteria which decompose the bark in a few months. In this case, however, the elimination of the nitrogen makes the composted residue unusable for fertilizer. Some ten years ago a process was developed, protected by Finnish Pat. No. 44,124, whereby plant poisons present in bark could be removed from it and nitrogen and other mineral nutrients were not eliminated.
Waste bark treated by this process is very suitable for fertilizer. In the process in question, crushed waste bark, stored in piles, is cooked for some time together with waste molasses from the sugar industry.
In this case also, the nutrients present in the lignin become soluble to such an extent that plants are able to use them.
Said process has, however, one disadvantage in that the cooking process incorporated in it makes it unsuitable for continuous production. Furthermore, a more complete decomposition of the nutrients present in the lignin would tend to further improve the availability of the respective nutrients to plants.
Thus, it is an object of the invention to achieve an improvement over the known process and to overcome the disadvantage mentioned above.